Technique could stop transplant organ waste

More than 60% of hearts and lungs donated for transplantation are thrown away because they cannot be kept on ice for more than four hours. Now a new technique might help stop this waste and eliminate waiting lists.

Preservation through cooling tissues using very low temperatures between -160 and -196 °C is not the problem, but re-warming them is. Tissue often suffers major damage during this process making the organs unusable.

But now, researchers from the University of Minnesota have shown a way this process may be made more reliable, having successfully rewarmed large-scale animal heart valves and blood vessels preserved at very low temperatures.

Their work was published in Science Translational Medicine.

“This is the first time that anyone has been able to scale up to a larger biological system and demonstrate successful, fast, and uniform warming of hundreds of degrees Celsius per minute of preserved tissue without damaging the tissue,” said University of Minnesota mechanical engineering and biomedical engineering professor John Bischof, the senior author of the study.

He said that in the past, researchers have only been able to show success at about 1 millilitre of tissue and solution. This study scales up to 50 millilitres, which suggests it could one day scale up to re-warm organs.

The new method uses silica-coated iron oxide nanoparticles, activated by electromagnetic waves to act as tiny heaters around the tissue. This leads to uniform warming that can be up to 100 times faster than previous methods, while the nanoparticles are washed away after the process is completed.

In the experiments, none of the tissues were damaged where as control samples rewarmed slowly over ice or using convection heating were.

The next step is to try the technique on rodent organs before scaling up to pig and, finally, human organs.

The researchers said the technology might also be used in other applications, such as delivering lethal pulses of heat to cancer cells.